i found that this is a bug
Bug ID 117062 Title "Sensor PS_1_Present is failing to operate!" on F700 filers

specific to F7XX
there is nothing to do

it's annoying but not important ...



Scott Brynen wrote:
I've seen this on our systems as well.  Let me know if you find a solution, 
it's quite annoying (although our F740s are essentially retired).



On Monday 27 September 2004 09:20, Stephane wrote:
  
does anyone get such message just after the os boot :
<<
....................................................................
....................................................................

NetApp Release 6.5.2R1: Wed Sep  8 17:00:29 PDT 2004
Copyright (c) 1992-2004 Network Appliance, Inc.
Starting boot on Fri Sep 24 12:58:19 GMT 2004
Sensor PS_1_Present is failing to operate!
Sensor PS_2_Present is failing to operate!
...
<normal boot>


i don't know if this is related to a bug in Ontap
a problem in the mother board
or a misconfiguration between 652 and old F7XX power supply
(this appeared on an F740)

environment commands show no problems
powersupply at the rear are ok
unplugging a PS generate an alert normally